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THE ENDOCRINE SYSTEM. Chapter 16. OVERVIEW. Group of unimpressive, discontinuous organs Coordinates and integrates body activity through the use of hormones produced in ductless glands. Differs from nervous system because its work is strictly chemical
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THE ENDOCRINE SYSTEM Chapter 16
OVERVIEW • Group of unimpressive, discontinuous organs • Coordinates and integrates body activity through the use of hormones produced in ductless glands
Differs from nervous system because its work is strictly chemical • Exocrine glands use ducts to deliver their secretions
Organs • Pineal, hypothalamus, pituitary, thyroid, parathyroid, thymus, adrenal, pancreas, testis, ovary, placenta, tumors, cells within the digestive tract, heart, kidney, etc.
Adrenal 5 1 1 Pineal Pituitary 1 2 Thyroid 2 Pancreas 6 3 Ovaries 8 4 9 Testes Digestive hormones 7 Thymus 4 Hypothalamus 1 5 Parathyroid 3 6 7 8 9
tropic hormones hypothalamus thyroid-stimulating hormone (TSH) antidiuretic hormone (ADH) posterior pituitary Thyroid gland anterior pituitary Kidney tubules adrenocorticotropic hormone (ACTH) oxytocin Muscles of uterus gonadotropic hormones: follicle- stimulating hormone (FSH) & luteinizing hormone (LH) melanocyte-stimulating hormone (MSH) growth hormone (GH) prolactin (PRL) Adrenal cortex Melanocyte in amphibian Mammary glands in mammals Bone and muscle Ovary Testis
Hormones • Chemicals released into extracellular fluids that regulate metabolic functions of other cells • Ex: growth, development, metabolism immune response, electrolyte & water balance, blood pressure, RBC production
Hormones fall into one of 2 categories: • Amino-acid based – most hormones in this category; ex: thyroxine, insulin, melatonin, ADH, etc. • Steroid- (cholesterol based) ex: sex hormones (estrogen, FSH, LH, testosterone), aldosterone
Function by binding to and influencing activity of a target cell (cell containing receptors for that hormone); ex: most body cells have receptors for human growth hormone and thyroxine • Provoke a secondary messenger activity OR • Directly influence DNA activity of the cell
Once bound, hormones: • Change plasma membrane permeability • Promote production of regulatory molecules; enzymes • Activate or deactivate enzymes • Induce secretory activity of the cell
Control is by feedback mechanism • Ex: Negative Feedback • Gland is stimulated due to low levels of hormone • Hormone is released • Hormone levels increase in bloodstream • Increased levels deactivate gland
high low Maintaining homeostasis hormone 1 lowersbody condition gland specific body condition raisesbody condition gland Negative FeedbackModel hormone 2
Nervous System Control Feedback high low Controlling Body Temperature nerve signals brain sweat dilates surfaceblood vessels body temperature brain constricts surfaceblood vessels shiver nerve signals
Endocrine System Control Feedback pancreas high liver low pancreas liver Regulation of Blood Sugar insulin body cells takeup sugar from blood liver storessugar reducesappetite blood sugar level liver releasessugar triggershunger glucagon
Endocrine System Control Feedback pituitary nephron nephron high JuxtaGlomerularApparatus low nephron (JGA) adrenalgland Blood Osmolarity ADH increasedwaterreabsorption increasethirst blood osmolarity blood pressure increasedwater & saltreabsorption renin aldosterone angiotensin
Endocrine System Control Feedback Regulation of Blood Calcium calcitonin kidney filters Ca++ Ca++ depositedin bones high blood calcium level(10 mg/100mL) Ca++uptakein intestines low activated Vitamin D parathyroid bones release Ca++ kidney reabsorbs Ca++ PTH
Feedback corpusluteum ovary yes no Female reproductive cycle eggmatures & is released(ovulation) builds up uterus lining estrogen progesterone fertilized egg FSH & LH maintainsuterus lining HCG pregnancy progesterone GnRH corpus luteum breaks down progesterone drops = menstruation maintainsuterus lining hypothalamus
Control falls into one of 3 categories: • Hormonal stimuli – Ex: FSH from pituitary stimulates ovary to release progesterone and estrogen; this in turn shuts down FSH = rhythm
Humoral stimuli – Ex: blood sugar levels stimulate pancreas to release insulin; this lowers sugar levels which in turn reduces insulin production
Neural stimuli – Ex: stress triggers adrenal gland to release adrenaline
Organs/Hormones • Anterior Pituitary – HGH, TSH, ACTH, FSH, LH, PRL • Hypothalamus – oxytocin, ADH • Thyroid – thyroxine, calcitonin • Parathyroid – PTH
Adrenal – glucocorticoids, androgens, aldosterone, adrenaline • Pancreas – insulin, glucagon • Gonads – testosterone, estrogen, progesterone • Pineal – melatonin • Thymus – thymopoietin, thymosin
Goiter Iodine deficiency causes thyroid to enlarge as it tries to produce thyroxine
Robert Wadlow 1918-1940 8' 11" Excessive HGH
Hyperthyroidism Graves - hyperthyroid hypothyroidism